How to Calculate Resistance, Current, and Effective Resistance in a Series Circuit

Given the data of two lamps rated 60W; 240V and 100W, 240V respectively connected in series to a 240V power source:

a) What is the resistance of each lamp?

b) What is the effective resistance of the circuit?

c) How much current is passing through the lamps?

Answer:

See the answers below.

The total power of the circuit is equal to the sum of the powers of each lamp.

P = 60 + 100 = 160W

Now, with a voltage source of 240V, we can find the current in the circuit using the formula P = V * I.

I = P / V = 160 / 240 = 0.67 amp

Therefore, the answer for c) is 0.67 amp

Using Ohm's law, we can find the resistance of each lamp.

a) For the 60W lamp:

R = V^2 / P = 240^2 / 60 = 133.33 ohms

b) For the 100W lamp:

R = V^2 / P = 240^2 / 100 = 225 ohms

To find the effective resistance of the circuit in series, we sum the resistances:

Effective resistance = 133.33 + 225 = 358.33 ohms